Mass spectrometry (MS) is a powerful analytical technique that is used for the qualitative and quantitative identification of organic molecules, peptides, proteins and nucleic acids. MS offers speed, accuracy and high sensitivity.
Key components of a mass spectrometer are the ion source, ion coupling optics, mass analyser and detector. The ion source transforms analyte molecules into a stream of charged particles, or ions, through a process of electron addition or subtraction. The ions can be ‘steered’ using electric or magnetic fields. Ion coupling optics or lenses collimate the ion flux from the ion source into the mass analyser. The analyser separates ions by their mass to charge ratio. Several different kinds of mass analyser are known in the art, including, but not limited to; magnetic sector, quadrupole, ion trap, time of flight and cycloidal. The ions exit the analyser in order of mass to charge ratio and in so doing produces a mass spectrum which is a unique signature or ‘fingerprint’ for the analyte. Ions are directed to a detector where they impact and discharge an ion current which may be counted and amplified by signal electronics before being displayed on a computer screen as a mass spectrum. The detector is normally an electron multiplier. These components together form the analytical sub-system of the mass spectrometer system.
Until recently, these mass spectrometer components have been manufactured using conventional engineering techniques such as machine tools. This technology has been the mainstay of the mass spectrometer industry and is the basis of almost all products on market. Several attempts have been made to miniaturise and integrate these components using silicon micromachining, or MEMS technology, some of which are described in our previously filed British applications, GB 0202665.6 and GB 0217815.0. The principle advantages of miniaturised mass analysers are the significantly reduced system requirements, in particular smaller power supplies, electronics and vacuum systems, an example of which is described in our earlier application, GB 0403122.5. This dividend is a consequence of the scaling laws associated with geometrically reduced electrical fields, and the shorter mean free path between collisions of molecules.
Other mass spectrometer system components include vacuum pumps, a vacuum chamber, drive electronics, data acquisition electronics, power supplies and enclosures.
As mentioned above, conventional mass spectrometer components are manufactured and assembled using machine tools and other workshop practices. Because mechanical precision is critical to the final performance of the mass spectrometer, these parts are fixed in place and are normally only dismantled, cleaned and re-assembled by a trained technician using proprietary tooling. Periodic cleaning of the mass analyser, ion optics and ion source is necessary because of a build-up of residual sample coatings during prolonged operation. These residues cause ‘clogging’ of apertures, deteriorating performance and cross-contamination of samples. Regular preventative maintenance is also needed to avoid burn-out of certain parts with a definite lifetime like the filaments and electron multiplying detectors. The entire maintenance and cleaning process can take several days to fully dismantle, clean, re-assemble and, if necessary replace, the core components and to pump down the system to full vacuum. This ‘downtime’ has a substantial impact on the availability, research chemist productivity and overall cost of ownership of this expensive asset.
There is therefore a need to provide an improved mass spectrometry system that overcomes these and other disadvantages associated with the prior art.